摘要:

Positive‐ion observations made on the twin Vela 3 satellites are used to study the plasma flow pattern in the ‘twilight’ regions (near 90° from the subsolar point) of the earth's magnetosheath. Observations from January to May 1967 reveal a persistent deviation from symmetry about the sun‐earth line. Both simultaneous measurements by satellites on opposite sides of the magnetosheath and long‐term averages indicate a flow pattern whose line of symmetry makes an angle of 8° ± 1° with the sun‐earth line, and ∼6° with the direction of the incident solar wind. This tilting of the flow pattern is in good agreement with Walters' 1964 prediction of the effect of the interplanetary magnetic field on the post‐bo

ISSN:0148-0227    

DOI:10.1029/JA074i011p02799

年代:1969

数据来源: WILEY

摘要:

The direction of the solar wind has been measured by analyzing the data obtained with the MIT Faraday cup on the IMP 1 satellite. During the period November 27, 1963, to February 24, 1964, the solar wind was, on the average, in the ecliptic plane (50% of cases between −2° and +2°) and came from west of the sun on 72% of the cases; the average value of the ecliptic longitude was −1.5°. If a systematic error of 1° is allowed, the above figures become 56% and 86% in the two extreme cases. This result indicates that, in the above period of time, the solar wind has tendency to anticorotate with

ISSN:0148-0227    

DOI:10.1029/JA074i011p02807

年代:1969

数据来源: WILEY

摘要:

The causes of 19 worldwide changes in the earth's magnetic field, occurring between June and December 1967, were determined by examining magnetic field and plasma data for the solar wind near the earth. Seven of the events were classified as storm sudden commencements (ssc) and 4 as sudden impulses (si) by most stations reporting them. All of the ssc's were caused by hydromagnetic shocks. Two of the si's were negative impulses (si−) and were caused by tangential discontinuities across which the density decreased. The other 2 si's were distinct pulses in the magnetograms, for which we suggest the designation pl+, and were caused by dense spots in the solar wind with dimensions ≈0.005 AU. There was no consensus among the reporting magnetic observatories as to whether the remaining 8 events should be called si's or ssc's. Five of these events were caused by shocks and the other 3 by tangential discontinuities in the solar wind, but there seems to be no sure way to predict the type of structure from the shape of the magnetogram pulse. The rise time of the impulse in theHcomponent in the magnetogram is apparently determined by something other than the type, the speed, or the thickness of an interplanetary discontinuity that caused the ev

ISSN:0148-0227    

DOI:10.1029/JA074i011p02815

年代:1969

数据来源: WILEY

摘要:

Measurements of the interplanetary magnetic field between the orbits of the earth and Mars were used to study the radial dependence of the field. The measurements were obtained with Mariner 4 over the period from November 28, 1964, to July 14, 1965, during which the spacecraft was in transit to Mars. For the strength of the quiet‐day field the best‐fit power‐law function of heliocentric rangerwasB= 4.13 (r/r0)−1.25, where 1.0 AU

ISSN:0148-0227    

DOI:10.1029/JA074i011p02826

年代:1969

数据来源: WILEY

摘要:

The low‐energy solar protons and alpha particles detected during the May 28 (day 148), 1967, solar flare are used as ‘probes’ to investigate the properties of the interplanetary medium during the course of the event. The lower energy fluxes exhibit characteristics of particle storage either at the sun or in interplanetary space. The higher energy particle fluxes exhibit ‘classical’ west limb flare profiles and are fit both to a simple isotropic diffusion‐with‐boundary model and to a radial dependent scattering center model. The diffusion coefficient model of Jokipii is used with the results of a fit to the exponential decay of the event to predict an ƒ−3dependence of the power spectral density of the interplanetary magnetic field fluctuations (assuming a boundary location independent of rigidity). The ratio of particle fluxes before and after a sudden, discontinuous flux decrease (attributed to a sector boundary) is found to be ∼R³ for protons and ∼R6for alphas for particles with rigidities ≲ 200 Mv. Significant velocity dispersions are discovered in three of the flux modulations during the onset stage of the event. The velocity dispersions in one of these modulations could be interpreted as due to a modulating region located ∼0.03 AU from the earth. It is speculated that this region was responsible for an sc at the e

ISSN:0148-0227    

DOI:10.1029/JA074i011p02851

年代:1969

数据来源: WILEY

摘要:

Using the proton data collected by the Vela 4 energetic particle telescopes during the period May 21‐June 8, 1967, a comparison has been made of the 0.7‐ to 40‐Mev proton fluxes inside and outside the magnetotail at 19RE. This comparison has yielded information pertaining to the mechanism by which protons can enter the magnetotail. Measurable delays in the propagation of sudden flux changes into the magnetotail were always observed, and they varied between 15 minutes and 2 hours; most delays were between ½ and 1 hour. Some fluctuations were smoothed or broadened by an amount comparable to the delay time, but the longer‐delay events were frequently not significantly smoothed. The delays were at best weakly energy dependent, and smoothing was most pronounced at the lowest proton energies. The fluxes inside the magnetotail or within ∼1REof the magnetopause were much more isotropic than those farther from the magnetopause or in the interplanetary medium. A comparison of these results with diffusive (multiple scattering) and free access (open tail) mechanisms reveals areas of disagreement with both: a long diffusion delay time and its dependence on the inverse of the particle energy are not observed, and the magnitude of the delays suggests that field line interconnectionnearthe earth is not an important source of magnetotail protons. We conclude that the observations may be explained by a combination of multiple scattering near and within the magnetotail and merging of the earth's magnetic field with the interplanetary field far (∼1000RE

ISSN:0148-0227    

DOI:10.1029/JA074i011p02869

年代:1969

数据来源: WILEY

摘要:

Observations of ∼10‐Mev protons were made over the polar regions by an ionization chamber during two solar proton events on March 24, 1966, which were separated by ∼3.5 hours. Short‐term fluctuations in the ionization were observed with factor of 2 changes occurring in ∼30 sec or ∼220 km. A nearly identical ionization chamber at 10–16REsunward observed no short‐term fluctuations, and these differences are interpreted as spatial effects due to the field structure over the poles. The fluctuations occur mainly when the proton density outside the magnetosphere is increasing rapidly (by a factor of 2 per ∼10 minutes) and when the flux is highly anisotropic. Most of the fluctuations disappear in ∼2 hours, but similarities between the fluctuatons observed during the two solar proton events suggest that the modulation is not interplanetary in origin, and that the magnetospheric field structure causing the modulation retains the same pattern for a period of 3.5 hours. The fluctuations may be due to particles following different paths through the magnetosphere and connecting to different parts of the anisotropic flux b

ISSN:0148-0227    

DOI:10.1029/JA074i011p02881

年代:1969

数据来源: WILEY

摘要:

Auroral absorption occurrence patterns that can be simply mapped onto the earth's magnetotail have been developed as a function ofKp. The resulting polar plots show several interesting features. One is the occurrence of intense absorption events at about 60° geomagnetic latitude near noon under relatively quiet magnetic conditions. A more interesting feature appears in the night sector where the pattern of intense absorption occurrence divides into two distinct regions with increasing longitudinal separation asKpincreases. From this observation we infer how the width of the magnetotail neutral sheet source changes as a function ofKp

ISSN:0148-0227    

DOI:10.1029/JA074i011p02891

年代:1969

数据来源: WILEY

摘要:

The stochastic heating of protons by a random magnetosonic wave propagating normal to the magnetic field is suggested as an explanation of the observation that the protons are hotter than the electrons in the plasma sheet of the magnetotail. A perturbation analysis is used to find the proton trajectories under the influence of the electric and magnetic fields of the driving wave. The gradients of the field quantities across a proton orbit are included by using the first term in a Taylor series expansion. The inclusion of the field gradients and particle drifts gives the result that the heating depends not only on the energy in the wave spectrum at the gyrofrequency but also on that at the first harmonic of the gyrofrequency, and suggests, furthermore, that the faster protons are heated more strongly with the result that their distribution function can be broadened, consistent with observation. A nonlinear mechanism that can decouple the particles from the wave is suggested, and it is shown to yield proton energy gains of the correct order of magnitude for the plasma sheet.

ISSN:0148-0227    

DOI:10.1029/JA074i011p02899

年代:1969

数据来源: WILEY

摘要:

The propagation of flare‐generated shock waves through the solar wind is examined using numerical solutions of the time‐dependent hydrodynamic equations. These solutions are valid for all shock strengths, including the intermediate values that have been observed in the solar wind, and take into account the variation of the properties of the ambient solar wind. The entire range of time scales for energy deposition in the disturbance, from impulsive (producing ‘blast waves’) to continuous deposition, is considered. For the former class of disturbances the solutions approach a limiting form dependent only on the total energy in the wave. Relationships among the energy, shock strength at 1 AU, and transit time to 1 AU are found in the blast wave limit. For disturbances with energies near 1031ergs, the wave propagates from the sun to 1 AU in ∼60 hours, and is preceded by an intermediate strength shock at the latter distance. Both the transit time and shock strength are in good agreement with directly observ

ISSN:0148-0227    

DOI:10.1029/JA074i011p02908

年代:1969

数据来源: WILEY